source for low quantity custom bolt 2

[dgowans]

I'm looking for a prototype source for a custom bolt. I need to obtain a small quantity of an 18-18 bolt. According to the information I could dig up (which isn't much), this is a thread that was standard a long time ago but has since been obsoleted. I looked in a Machinery's handbook from 1964 and this thread wasn't listed so I assume it went obsolete before then.

This thread is somewhere between a 1/4-20 and a 5/16-18 - I've seen 5/16-18 threaded rod re-tapped on the end to make an 18-18, but that's not what I want.

We've got production quantity quotes in and the lead time is understandably rather long. We have an immediate need for some of these bolts to go on customer samples of a new product and I'm looking to get my hands on a small quantity of these. If anyone could point me toward a shop that does this kind of custom work I'd be most appreciative.

 

[Berniedog]

Try Wecall. Talk to Paul Doherty @440-437-8202

 

[dik]

BrianRost... does Wecall do custom bolts. If they do, I'll keep their name and number on file.

Dik

 

[dgowans]

I just spoke with Wecall and was told they typically only do nuts - big ones at that.

 

[JohnNabors]

Any job shop in your area should be able to make the bolts for you.

John Nabors

'Heaven is the place where the police are British, the chefs are Italian, the mechanics are German, the poets are French, and it is all organized by the Swiss.

Hell is the place where the police are German, the chefs are British, the mechanics are French, the poets are Swiss and it is all organized by the Italians.'

 

[drawoh]

dgowans,

Is there any reason you cannot take this to a machine shop? If you can somehow specify the thread, this sounds like a perfect job for a CNC lathe.

JHG

 

[dgowans]

I've got calls into several local places on this. It's kind of a situation where we got caught with our pants down and we're now scrambling to meet immediate needs. I was just looking for sources that some of you may have used in the past for this sort of thing.

 

[arto]

These guys did a great job for me on some tapered dowels:
lots of custom & aerospace stuff

http://www.reidproducts.com/

 

[NickE]

I guess I just want to know why you are using a completly non-standard thread form?

 

[dgowans]

My product is a field retrofit to existing equipment that is in some cases 60-80 years old. Believe me, my life would be a lot easier if I could spec a 5/16-18........

 

[NickE]

OK, that makes sense.. I was thinking it was some lame attempt to prevent reverse engineering, or user replacement of these screws...

Soem generally useless questions follow:

Is this a "whitworth" thread?

Can you drill and tap this out to something only slightly bigger? M8x0.8?

Dang thats gotta be a PITA! Good luck!

 

[dgowans]

Some generally useless answers........

What's a Whitworth thread?

Nope, drilling and tapping is not an option for various reasons that I won't go into. Suffice it to say that all the arguments against drilling and tapping are 100% valid.

 

[CoryPad]

Whitworth - old British thread form with 55 degree angle instead of 60 deg for current unified and ISO metric threads.

http://www.boltscience.com/pages/screw4.htm

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[JohnNabors]

A Whitworth thread is a mostly obsolete British thread standard that has a 55 degree flank angle and specified root and crown radii sort of like the Unified J-thread. The specification is covered in the British standard BS 84:1956.


John Nabors

'Heaven is the place where the police are British, the chefs are Italian, the mechanics are German, the poets are French, and it is all organized by the Swiss.

Hell is the place where the police are German, the chefs are British, the mechanics are French, the poets are Swiss and it is all organized by the Italians.'

 

[JohnNabors]

Yeah- what Cory said! ;>P

John Nabors

'Heaven is the place where the police are British, the chefs are Italian, the mechanics are German, the poets are French, and it is all organized by the Swiss.

Hell is the place where the police are German, the chefs are British, the mechanics are French, the poets are Swiss and it is all organized by the Italians.'

 

[dgowans]

Thanks for the info on the Whitworth, but that's not what I'm looking for. We've seen documentation on the product we're fitting to that specifically calls out an 18-18 thread.

Not enough expletives in the world to describe my loathing for this thing......

 

[cliffy]

I can probably make you a small quantity of whatever you need. Some questions: too what does the "18-18" refer? If the second "18", pitch, is 18 tpi, what does the first "18" mean?
Do you have a requirement for head size, material quality i.e. tensile and yield or other specs these need to fulfill?

My hovercraft is full of eels.

 

[dgowans]

Cliffy,

The first 18 refers to what is now an obsolete size, similar to #8, #10, etc. I probably should have described this crazy thing as #18-18.

If you've got a website with contact information we can discuss this off-line.

 

[cliffy]

http://www.praxairservices.com/

go to "contact us" then down to Tucson, AZ to get one of our numbers. Ask for Brian

My hovercraft is full of eels.

 

[cliffy]

dgowans: I just found some info on the thread mentioned above. You may get a die made for this application at Western Tap Manufacturing,

http://www.westerntap.com/

if you want to do this yourself.
I spoke to Rob (he's a genius with this stuff) and he knew exactly what I was talking about.
This old designation, which goes up to #22 or so, is the number of 0.013" times the number plus 0.060".
Confused? Me too! In your case, 18 X 0.013 + 0.060 = 0.294" gives the major diameter.
Western also offers full engineering services for this sort of thing. Rob said it would run you about $50 or so.

My hovercraft is full of eels.